Przewalski’s Horse - Equus prjevalskii [disputed, generally accepted as Equus ferus przewalskii]
The Przewalski’s horse, or takhi, is the only “true” wild horse remaining in the world, and is distinct from Equus ferus caballus, the domesticated horse. Though Przewalski’s horses and domesticated horses can interbreed and produce fertile offspring, the Przewalski’s horse has an extra pair of chromosomes, distinctive dentition, and a convex profile (“Roman nose”) uncommon in most breeds of domestic horse. The subspecies is believed to have diverged from Equus ferus ferus around 125,000 years ago, but the two groups interbred for at least 25,000 years before true geographical isolation began.
The discovery of the takhi in the Mongolian steppes in 1881 was followed by the collection of entire herds through hunting and rounding up to be kept in zoos. The last wild herd was spotted in 1967, and the last individual was spotted in 1969. The most genetically diverse captive herd (living in Askania-Nova in Ukraine) was slaughtered by former German soldiers in the late 1940s for unknown reasons.
Fortunately for conservation efforts, the very few individuals remaining in the world by 1977, when the species was declared “Extinct in the Wild”, proved to be very healthy, at least in terms of genetic vitality. Careful breeding programs started by the Foundation for the Preservation and Protection of the Przewalski’s Horse (FPPPH) in that same year ensured that the genetic diversity remained as strong as possible, given the tiny population. Twelve to fifteen individuals managed to produce small herds in several zoos and preserves, and the population grew at a steady pace for a decade and a half, before the first individuals were re-introduced to the wild, in 1992. Despite
After that first herd of 16 genetically distinct individuals from several zoos was introduced into the Gobi Desert, and successfully formed a herd with numerous healthy foals, Przewalski’s horse was re-classified from “Extinct in the Wild” to “Critically Endangered”. As of 2008, three stable-and-growing herds exist in the wild, in Mongolia and the prohibited-access zone around Chernobyl, Ukraine (a surprisingly good wildlife preserve!). They’re currently considered “Endangered”, and their population outlook is positive, with genetic diversity programs continuing in both zoos and the wild herds.
Proceedings of the Zoological Society of London. 1902.